1. Field of the Invention:
The present invention relates to a diamond cutting saw blade for cutting concrete, asphalt, stone and other materials.
2. Discussion of the Related Art:
There has been known a conventional diamond cutting saw blade in which a plurality of segment chips are fixed to the outer periphery of a disc-shaped iron substrate.
The diamond cutting saw blade of this segment type is superior to that of the continuous type, in which a diamond segment layer is fixed to the overall outer peripheral surface of a substrate, in the emission of cutting powder (dust) produced when cutting, because the former has the action of slits formed between the segment chips.
However, even in this segment type, complete emission of the cutting powder is difficult, so a cutting saw blade with superior emission of cutting powder is desired.
In such a diamond cutting saw blade, a lot of frictional heat is generated when cutting. This phenomenon more remarkably occurs in the intermediate region of the segment chip, causing burning of the cutting saw blade, lowered cutting capability, and the like.
Under the above circumstance, various attempts to solve the above problems with the conventional device have been conducted. For example, Utility Model Unexamined Publication No. Sho 61-35742 discloses a cutting saw blade in which a concave portion is defined in the outer periphery of a segment chip. With such a construction, the cutting powder emitting effect can be improved to some degree.
However, the concave portion disclosed by the above publication has a square cross section where the bottom surface and the side surface of the concave portion intersect each other, and cutting powder is liable to remain in the corner where the bottom surface and the side surface intersect each other, hindering the effective emission of cutting powder. Moreover, in such a construction, the temperature rise in the center of the segment chip cannot be abated.
Ways this problem can be solved include subdividing the segment into several parts so that the number of slits is increased, or widening the slits. However, when widening the slits, the segment chip intermittently abuts against an object to be cut when cutting, causing vibration. When increasing the number of slits, the length of the segment chip per one is made shorter in such a manner that the adhesion area of the chip and iron substrate is reduced, thereby making it difficult to maintain a safe fixing force.
For that reason, the present inventors and other persons have proposed in Japanese Utility Model Unexamined Publication No. Sho 62-172560, that each of the concave portions formed on both ends of the outer periphery of a segment chip are of a trapezoidal concave portion which expands outwardly, and a cool water supply concave portion is defined approximately on the intermediate position in the inner periphery of the segment chip. In such a concave structure, the cutting powder during cutting is liable to be discharged outwardly along the tapered surface of the trapezoid, thereby enabling an improvement in the emission of cutting powder.
According to recent research in this field, it has been found that cutting powder still remains in the corner where the bottom surface and the side surface of the trapezoidal concave portion formed in the segment chip intersect each other, so that it cannot be completely emitted. In particular, there is a case where when cutting hard concrete, stress in the corner where the bottom surface and the side surface of the trapezoidal concave portion intersect results in the concave portion cracks and being damaged.